1. Field of the Invention
The invention relates to a device and method for determining a depth of an incision for deployment of a closure system for blood vessel punctures.
2. Brief Description of the Related Art
A large number of diagnostic and interventional procedures involve the percutaneous introduction of instrumentation into a vein or artery. For example, coronary angioplasty, angiography, atherectomy, stenting of arteries, and many other procedures often involve accessing the vasculature through a catheter placed in the femoral artery or other blood vessel. Once the procedure is completed and the catheter or other instrumentation is removed, bleeding from the punctured artery must be controlled.
Traditionally, external pressure is applied to the skin entry site to stem bleeding from a puncture wound in a blood vessel. Pressure is continued until hemostasis has occurred at the puncture site. In some instances, pressure must be applied for up to an hour or more during which time the patient is uncomfortably immobilized. In addition, a risk of hematoma exists since bleeding from the vessel may continue beneath the skin until sufficient clotting effects hemostasis. Further, external pressure to close the vascular puncture site works best when the vessel is close to the skin surface and may be unsuitable for patients with substantial amounts of subcutaneous adipose tissue since the skin surface may be a considerable distance from the vascular puncture site.
More recently, devices have been proposed to promote hemostasis directly at a site of a vascular puncture. One class of such puncture sealing devices features an intraluminal anchor which is placed within the blood vessel and seals against an inside surface of the vessel puncture. The intraluminal anchor may be used in combination with a sealing material positioned on the outside of the blood vessel, such as collagen. Sealing devices of this type are disclosed in U.S. Pat. Nos. 4,852,568; 4,890,612; 5,021,059; and 5,061,274.
Another approach to subcutaneous blood vessel puncture closure involves the delivery of non-absorbable tissue adhesives, such as cyanoacrylate, to the perforation site. Such a system is disclosed in U.S. Pat. No. 5,383,899.
The application of an absorbable material such as collagen or a non-absorbable tissue adhesive at the puncture site has several drawbacks including: 1) possible injection of the material into the blood vessel causing thrombosis; 2) a lack of pressure directly on the blood vessel puncture which may allow blood to escape beneath the material plug into the surrounding tissue; and 3) the inability to accurately place the absorbable material plug directly over the puncture site.
The use of an anchor and plug system addresses these problems to some extent but provides other problems including: 1) complex and difficult application; 2) partial occlusion of the blood vessel by the anchor when placed properly; and 3) complete blockage of the blood vessel or a branch of the blood vessel by the anchor if placed improperly. Another problem with the anchor and plug system involves reaccess. Reaccess of a particular blood vessel site sealed with an anchor and plug system is not possible until the anchor has been completely absorbed because the anchor could be dislodged into the blood stream by an attempt to reaccess.
Such puncture sealing devices are generally used in conjunction with a cannula or arterial dilator which dilates an access tract in the tissue before inserting the sealing device for placing the intraluminal or sealing plug. By using the cannula to dilate the access tract, the sealing device can be easily advanced into the tissue toward the vascular puncture. A conventional cannula C having a constant diameter lumen which is sized to closely accommodate a guidewire is shown in FIG. 1. Alternatively, the cannula may have a lumen with a diameter which narrows at the distal end. When these conventional cannulas are advanced into the access tract, the cannulas often encounter scar or muscular tissue that requires substantial force to advance the cannula through these layers. As shown in FIG. 1, the cannula C which has a constant diameter lumen may enter the vascular puncture while being advanced into the access tract, or the cannula C will bounce against a wall of the blood vessel rather than accurately locate the blood vessel wall. A dilator D, shown in FIG. 2, has a tapered distal end for dilating a tissue access tract. The tapered dilator D cannot accurately locate a puncture because the distal end of the dilator passes through the blood vessel puncture. Accordingly, the sealing plug may not be accurately placed over the puncture site when a sealing device is used with the cannula C or the dilator D.
Accordingly, it would be desirable to provide a device and method for accurately determining the depth of an incision by accurately locating the blood vessel wall for properly placing a hemostasis promoting plug over the puncture site.